Language Elements

The descriptions of the policy and policy set structure sometimes refer to language elements like identifiers and strings. These elements are explained in this section.

Identifiers

Multiple elements in policies or policy sets require identifiers. E.g., a variable assignment expects an identifier after the keyword var - the name under which the assigned value will be available.

An identifier only consists of alphanumeric characters, _ and $, and must not start with a number.

Valid Identifiers

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a_long_name
aLongName
$name
_name
name123

Invalid Identifiers

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a#name
1name

A caret ^ before the identifier may be used to avoid a conflict with SAPL keywords.

Strings

Whenever strings are expected, the SAPL document must contain any sequence of characters enclosed by single quotes ' or double quotes ". Any enclosing quote character occurring in the string must be escaped by a preceding \, e.g., "the name is \"John Doe\"".

Comments

Comments are used to store information in a SAPL document which is only intended for human readers and has no meaning for the PDP. Comments are simply ignored when the PDP evaluates a document.

SAPL supports single-line and multi-line comments. A single-line comment starts with // and ends at the end of the line, no matter which characters follow.

Sample Single-Line Comment

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policy "test" // a policy for testing

Multi-line comments start with /* and end with */. Everything in between is ignored.

Sample Multi-Line Comment

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policy "test"
/* A policy for testing.
Remove before deployment! */